"Too bright were the eyes of Arien for even the Eldar to look on, and leaving Valinor she forsook the form and raiment which like the Valar she had worn there, and she was as a naked flame, terrible in the fullness of her splendor."

Arien (Q, pron. [ˈari.en], stem Ariend-) was a Maia who guided the Sun.

History

After the destruction of the Two Trees, Arien, a Maia was chosen by the Valar to guide a vessel made by Aulë which held the last fruit of Laurelin above the airs of Arda. This vessel was of course the Sun. In the days of the Two Trees Arien had tended Laurelin and was a spirit of fire, not unlike Balrogs before their downfall to shadow thanks to Melkor. She was therefore able to stand the heats of the Sun. It is said that she was mightier than Tilion, the Maia chosen to guide the Moon, who loved her and followed her through the night sky sometimes catching up to her and becoming burned and blackend by her heat.

Other Versions of the Legendarium

In other writings, Morgoth wanted to claim Arien as a wife, and ravished her, upon which she abandoned her body and "died", leaving the Sun to travel through the skies uncontrollably and burning parts of Arda the world. As well, it is stated in other abandoned writings that she was a Maia of Varda. It is not clear if it was Tolkien's intent to keep these elements in The Silmarillion tradition, had he lived long enough to publish it.